The present invention relates to a swirl disk and to a fuel injector.
An electromagnetically operable fuel injector in which a swirl-generating element is provided upstream from a valve seat is described in German Published Patent Application No. 196 37 103. The swirl-generating element is formed such that at least two flows of fuel are able to be generated that are radially offset from one another and run in a mutually enclosing or encircling manner in different directions. The system for generating the spray jet, which is made up of an inner and an outer flow having different orientations, and including flow paddles or multilayer swirl attachments as guiding elements on an orifice plate is quite complicated and is comparably expensive to produce. The swirl-generating element is designed such that either a swirling full-cone stream or a swirling hollow-cone stream emerges from the fuel injector.
The so-called multilayer electroplating for producing orifice plates that are particularly suitable for use in fuel injectors are described in German Published Patent Application No. 196 07 288. This manufacturing principle is for producing disks using multiple electroplating metal deposition of different patterns on one another, so that a one piece disk results. The micro-electroplating metal deposition in several surfaces or layers may also be used for producing the swirl plates of the present invention.
The swirl disk of the present invention has the advantage that it is able to be inexpensively produced in a particularly simple manner. A particular advantage is that the swirl disks are able to be produced simultaneously and extremely precisely in large numbers in a reproducible manner (high batch capability). Using the one-piece swirl disk of the present invention, it is possible to produce a swirling dual-jet characteristic of a spray device, in particular of a fuel injector, without any additional supplementary attachments or other auxiliary swirl-generating means.
It is particularly advantageous to produce the swirl disk using so-called multilayer electroplating. Due to their metallic design, such swirl disks are unbreakable and easily mountable, e.g. on injectors or other spray nozzles for fluids of any type. Using multilayer electroplating permits an extremely large freedom of design since the contours of the opening regions (inlet regions, swirl channels, swirl chambers, outlet openings) in the swirl disk may be freely selected. This flexible form design is advantageous especially in comparison with silicon disks, which have strictly defined attainable contours (truncated pyramid) due to the crystal axes.
Metallic deposition has the advantage of a particularly large material diversity especially in comparison with producing silicon disks. The most different metals having different magnetic properties and hardnesses may be employed in the micro-electroplating used for producing swirl disks.
It is particularly advantageous to construct the swirl disk including three layers by performing two or three electroplating steps for the metal deposition. In this context, the upstream layer represents a cover layer that completely covers the swirl chamber of a middle swirl-generating layer. The swirl-generating layer is formed by a plurality of material regions that form the contours of the swirl chamber and of the swirl channels due to their shaping and their geometric position with respect to one another. As a result of the electroplating process, the individual layers are built up on top of one another without separation points or joining points such that represent a continuously homogenous material. In this respect, the xe2x80x9clayersxe2x80x9d are to be understood as a mental aid.
In an advantageous manner, at least two, but also four or six swirl channels with which at least two different swirl directions are produced in the fuel are provided in the swirl disk. The material regions may have very different forms depending on the desired shaping of the swirl channels.
The fuel injector of the present invention has the advantage that a particularly high spray quality of a fuel to be sprayed as well as a desired double jet formation are achieved in a very simple manner for certain installation conditions and combustion-chamber designs. Therefore, the fuel injector of the present invention makes it possible to achieve a swirling dual-jet characteristic, the two jet branches forming a double swirl with their opposing swirl direction. As a result, an injector of an internal combustion engine allows among other things the exhaust-gas emission of the internal combustion engine as well as the fuel consumption to be reduced.
An example embodiment of a swirl disk includes a structure including a complete passage for a fluid, at least one inlet region, at least one outlet opening, a bottom base layer in which the at least one outlet opening is introduced, at least two swirl channels that empty into a swirl chamber, and a swirl-generating layer into which the swirl chamber is provided. The at least two swirl channels may be situated and positioned such that when a fluid flows through, at least two swirl flows are generated next to one another in opposite directions, each one forming its own jet branch, and the at least one outlet opening may be designed in the shape of an 8.
An example embodiment of a fuel injector for a fuel injection system of an internal combustion engine includes a longitudinal valve axis, an actuator, a fixed valve seat formed at a valve seat element, a movable valve part that cooperates with the fixed valve seat to open and close a valve, and a swirl disk situated downstream from the fixed valve seat and having a multilayer design. The swirl disk may include at least one inlet region and at least one outlet opening, the at least one outlet opening may be introduced in a bottom base layer of the swirl disk, the swirl disk may include a swirl chamber and at least two swirl channels that empty into the swirl chamber and are upstream from the at least one outlet opening, the at least two swirl channels may be situated and positioned such that when a fluid flows through, at least two swirl flows are generated next to one another in opposite directions, each one having its own jet branch, and the at least one outlet opening may be designed in the shape of an 8.
Corresponding advantages for the use on a fuel injector may be derived in a logical manner from the advantages specified with regard to the swirl disks since the simplified and particularly easily reproducible manufacturing method of the swirl disks in connection with the high functionality of the swirl production in fluid, fuel in this case, for the fuel injector also result in the advantages of high quality, uniform fine spraying, high variability in the jet forms, and a reduction in cost.